1. Field of the Invention
This invention relates to the field of laser projection patterning and more specifically to a system, apparatus, method and article of manufacture for providing real-time reflective mask creation and laser patterning.
2. Brief Description of the Prior Art
There is currently a need to produce precise laser patterns of inorganic or organic materials where the patterns define areas of desired material removal. Laser corrective eye surgery is one of many applications where precise customized ablation of predefined patterns is very important. Presently, mask patterning is achieved by one of several techniques: small spot scanning, slit scanning or by placing a transmissive mask in the beam path. While these methods can offer some level of customization, spot scanning accuracy is limited by spot size and positional accuracy, and masks have to be prefabricated at high cost. In addition, whenever a pattern needs modification a new mask pattern must be prepared which requires additional time and expense. In the case of laser corrective eye surgery, masks on hand may not offer close compliance to the individual surgery plan.
Another method for achieving desirable laser energy distribution over the work-piece surface uses active matrix of mirrors, such as the xe2x80x9cDigital Micro-mirror Devicexe2x80x9d (xe2x80x9cDMDxe2x80x9d) available from Texas Instruments(xe2x80x9cTIxe2x80x9d) and the xe2x80x9cThin Film Micromirror Arrayxe2x80x9d (xe2x80x9cTMAxe2x80x9d) available from Daewoo. However, neither, TI""s DMD devices nor Daewoo""s TMA devices are suitable for deep ultra-violet radiation applications. Laser eye surgery is performed at 193.3 nm wavelength, and most optical materials and process environments are very absorptive in this wavelength region. Creating highly accurate patterns with high optical efficiency poses a significant challenge. In laser eye surgery, patterns must be created as a part of the surgery procedure, and they must be based on corneal topography measurements. Furthermore, patterns may need to be changed during the course of surgery or several patterns may need to be layered over the same surface.
In the areas of non-tissue material processing, laser ablation techniques have been implemented that use transmissive masks as the patterning elements in lithographic projections systems where the illumination source is an excimer laser.
The present invention is directed to a novel, inventive and inexpensive approach that provides for real-time reflective mask creation and laser patterning.
In accordance with one aspect of the present invention, there is provided a system and method for ablating a surface of a work-piece. The system comprises: a radiation source for providing an ablating beam and a plurality of adjustable reflective masks having predetermined mask patterns thereon. The reflective masks are sequentially positioned relative to the radiation source and in the path of the ablating beam for reflecting certain portions of the ablating beam onto the surface of the work-piece.
In accordance with a second aspect of the present invention, there is provided a method for creating a reflective mask for ablation, comprising the steps of: sequentially selecting a reflective material having a reflective surface and generating a predetermined mask pattern on the reflective surface using either a printer or a micro-mirror array and laser combination.
In accordance with a third aspect of the present invention, there is provided a method for ablating a surface of a work piece, comprising the steps of: generating a predetermined mask pattern on a reflective substrate to produce a reflective mask; exposing the reflective mask to a radiation source to produce a reflected laser beam of certain shape; imaging the reflected laser beam onto the surface of the work-piece to ablate the surface of the work-piece; and repeating the forgoing steps, if necessary, to sequentially process a next predetermined mask pattern.